User's Manual Part 1

ZyXEL G-220F User’s Guide
Wireless LAN Network 2-7
Open System mode is implemented for ease-of-use and when security is not an issue. The wireless station
and the AP do not share a secret key. Thus the wireless stations can associate with any AP and listen to any
data transmitted plaintext.
Shared Key mode involves a shared secret key to authenticate the wireless station to the AP. This requires
you to enable the WEP encryption and specify a WEP key on both the wireless station and the AP.
Auto authentication mode allows the ZyXEL G-220F to switch between the open and shared key
authentication modes automatically. Use the auto mode if you do not know the authentication mode of the
other wireless stations.
2.6 Preamble Type
A preamble is used to synchronize the transmission timing in your wireless network. There are two
preamble modes: Long Preamble and Short Preamble.
Short preamble takes less time to process and minimizes overhead, so it should be used in a good wireless
network environment when all wireless stations support it.
Select Long Preamble if you have a ‘noisy’ network or are unsure of what preamble mode the access point
or the other wireless stations support as all IEEE 802.11b compliant wireless adapters must support long
preamble. However, not all wireless adapters support short preamble. Use long preamble if you are unsure
what preamble mode the wireless adapters support, to ensure interpretability between the ZyXEL G-220F
and the access point/wireless stations and to provide more reliable communication in ‘noisy’ networks.
Select Auto to have the ZyXEL G-220F automatically use short preamble when all access point/wireless
stations support it, otherwise the ZyXEL G-220F uses long preamble.
The ZyXEL G-220F and the access point/wireless stations MUST use the same preamble mode in order to
communicate.